Thinking Makes Us Pig Out

Food for thought: Intellectual activities make people eat more than
when just resting, according to a study that sheds new light on
brain food.

This finding might also help explain the obesity epidemic of an increasingly sedentary society in which people still have to think now and then.

Researchers split 14 university student volunteers into three groups
for a 45-minute session of either relaxing in a sitting position,
reading and summarizing a text, or completing a series of memory,
attention, and vigilance tests on the computer.

The scientists had determined beforehand that the thinking sessions consumed only three calories more than resting. After the sessions, the participants were invited to eat as much as they pleased.

Though the study involved a very small number of participants, the results were stark.

The students who had done the computer tests downed 253 more
calories, or 29.4 percent more than the couch potatoes. Those who had
summarized a text consumed 203 more calories than the resting group.

Blood samples taken before, during, and after revealed that
intellectual work causes much bigger fluctuations in glucose levels
than rest periods, perhaps owing to the stress of thinking.

The researchers figure the body reacts to these fluctuations by demanding food to restore glucose, a sugar that is the brain's fuel.
Glucose is converted by the body from carbohydrates and is supplied to
the brain via the bloodstream. The brain cannot make glucose and so
needs a constant supply. Brain cells need twice as much energy as other
cells in the body.

Without exercise to balance the added intake, however, such "brain food" is probably not smart. Various studies in animals have shown that consuming fewer calories overall leads to sharper brains and longer life, and most researchers agree that the findings apply, in general, to humans.

And, of course, eating more can make you fat.

"Caloric overcompensation following intellectual work, combined with
the fact that we are less physically active when doing intellectual
tasks, could contribute to the obesity epidemic currently observed in
industrialized countries," said lead researcher Jean-Philippe Chaput at
Laval University in Quebec City, Canada. "This is a factor that should
not be ignored, considering that more and more people hold jobs of an
intellectual nature," the researcher concluded.

Robert Roy Britt

Rob was a writer and editor at Space.com starting in 1999. He served as managing editor of Live Science at its launch in 2004. He is now Chief Content Officer overseeing media properties for the sites’ parent company, Purch. Prior to joining the company, Rob was an editor at The Star-Ledger in New Jersey, and in 1998 he was founder and editor of the science news website ExploreZone. He has a journalism degree from Humboldt State University in California.